Losing the plot in Really Old, Like Forty Five

Confusion in the Ark: Michela Meazza as Mimi and Paul Ritter as Monroe

Dementia is one of the greatest health issues facing us this century — and one of the most divisive.

Recently, Terry Pratchett has spoken of the contemporary "care burden" caused by Alzheimer’s disease, Martin Amis has called for euthanasia booths on street corners, and an Oxford University study has revealed that for every pound spent on dementia research 12 times as much is spent investigating cancer.

Tamsin Oglesby’s new play takes a mostly comic view of these concerns. It’s set in a dystopian future, where Britain is desperately overcrowded with infirm pensioners. Society is ravaged by Alzheimer’s, and citizens when they grow old are invited to move into a care facility called The Ark in return for becoming pawns in medical trials.

The unlovable bureaucrats behind The Ark occupy the upper tier of Lez Brotherston’s neat set, devising strategies for dealing with the ageing population. Meanwhile, below them, two elderly sisters and their brother grapple with the indignities of age and the effects of their decline on the rest of their family.

The contrast here between the personal and the political has bite, but there’s a frustrating uncertainty of purpose: is this satire, farce or a poignant danse macabre? Anna Mackmin’s production is strong on localised exuberance but the overall tone is erratic, and the play suffers from a surfeit of underdeveloped ideas.

As the two mature sisters, Judy Parfitt is regal before descending into angry bewilderment, while Marcia Warren’s performance is quieter and nicely judged. Others lack weight, though dancer Michela Meazza puts in a memorable turn as a robot nurse — part Gwen Stefani lookalike, part motorised swan.

Yet the fact that this mechanical figure is the most arresting feature of the production is telling. Really Old, Like Forty Five has a delightfully provocative title but not a beating heart. Until 20 April. Information: 020 7452 3000.

Really Old, Like Forty Five National Theatre: Cottesloe South Bank, SE1 9PX